For our Metronic Vue version we use Vue 3 with Bootstrap 5, at the moment, there is no official bootstrap-vue library that supports Bootstrap 5 and Vue 3.
In our current theme we are using plain Bootstrap 5 which doesn't require jQuery.
If you want to have form inside menu dropdown you can refer to the example in src/components/dropdown/Dropdown1.vue.
Regards, Lauris Stepanovs, Keenthemes Support Team